Physics Stories for the Lectures
An early model of a laser-propelled lightcraft.To reach space, we currently use the space shuttle, which has to carry tons of fuel and have two massive rocket boosters strapped to it to lift off the ground. Lasers would allow engineers to develop lighter spacecraft that wouldn't need an onboard energy source. The lightcraft vehicle itself would act as the engine, and light -- one of the universe's most abundant power sources -- would be the fuel. More
Crazy, huh? Until I ran into the fascinating book Living with Radiation, the First Hundred Years, self-published by Paul Frame and William Kolb, I had no idea that radiation was the basis for a huge quack-medicine industry that lasted for decades and took in millions. Read more.
The excavation of the LEP tunnel was the most formidable civil-engineering venture in the history of CERN and Europe's largest civil-engineering project prior to the Channel Tunnel. more..
On April 26, 1986 a disaster occurred in Ukraine (Chernobyl)that created the single worst nuclear power plant disaster so far. This reactor site was located on the Pripet River and consisted of four reactors. The Number Four reactor exploded and released an estimated 185 to 250 million curies of radioactivity into the environment. March 1979 a nuclear meltdown nearly occurred in the United States at the Three Mile Island nuclear power plant in Pennsylvania. more..
the
electron
orbitals of a
hydrogen atom can be found in different locations.
"The special theory of relativity owes its origins to Maxwell's equations of the electromagnetic field" — Albert Einstein
James Clerk Maxwell (June 13, 1831 - November 5, 1879) was a Scottish physicist, born in Edinburgh.Maxwell demonstrated that electric and magnetic forces are two complementary aspects of electromagnetism. He showed that electric and magnetic fields travel through space, in the form of waves, at a constant velocity of 3.0 × 108 m/s. He also proposed that light was a form of electromagnetic radiation.
How do fireflies produce light? There are several theories on how fireflies control the "on" and "off" of their photic organs. However, the exact mechanism(s) has yet to be worked out. The "Oxygen Control Theory" is based on the firefly turning on and off its light by controlling the oxygen supply to the photic organ for use in the chemical reaction. Read more..
Among the many odd ideas born of Einstein's theories of relativity, the one about twisted space-time certainly ranks high: A massive body like Earth creates geometrical dimples in space and, through its rotation, also pulls nearby space along with it. Astronomers verified the dimple effect back in 1919, but proof of the second, called frame dragging, has remained elusive. This month, some 87 years after Einstein cooked up his theory, NASA and Stanford University will launch an incredibly precise, $650 million experiment to put it to the test. read more...
Frame dragging
It is said, and rightly so, that cosmology is the branch of physics that asks the grandest questions. After all, few questions within science can equal the impact of: “Where does the universe come from?” or “What is the fate of the universe” or “Where does the matter we are made of come from?” Continue to read
About the Bose-Einstein Condensate—A New State of Matter. We know about solids, liquids, gases, and plasmas —these are the well-known states of matter. But now there’s another, called the Bose-Einstein condensate (BEC), and it’s been predicted for a long time. In 1924, Albert Einstein built upon work of Satyendra Bose to predict that ultracold atoms could form a new state of matter, with all the atoms overlapping. Continue to read...
But what is a laser? And what makes a laser beam different from the beam of a flashlight?
Lasers show up in
an amazing range of products and technologies. You will find them in everything from CD players
to dental drills to high-speed metal cutting machines to measuring systems.
They all use lasers.
In our everyday world, we observe all sorts of waves, including sound waves, water waves, and radio waves. But what about gravity waves?
...A star exists in a delicate
balance between the crushing force of gravity, on the one hand, and
the push of incredibly hot gases on the other. This...
...a catastrophic explosion as a supernova. (See neutrino astrophysics)
The force of gravity in the leftover object is so strong that the
electrons are...
Read more..
Hertz had succeeded in producing and receiving radio waves during his experiments in the mid-1880s, it was only across a short distance.
In 1892, Nikola Tesla arrived at the basic design for a radio. Four years
later, in 1896, Italian electrical engineer Guglielmo Marconi succeeded in
transmitting a radio signal 1.5 miles (2.4 kilometers). Within a few years
radio signals were being broadcast and received at distances up to 200 miles
(322 kilometers).
Read more.....
Nanotechnology is an umbrella term that covers many areas of research dealing with objects that are measured in nanometers. A nanometer (nm) is a billionth of a meter, or a millionth of a millimeter. In this edition of How Stuff Will Work, you will learn how nanomachines will manufacture products, and what impact nanotechnology will have on various industries in the coming decades. Read more....
Lunar eclipse 10/27/04,
Sunlight at the equator warms the air, making it rise and
thereby creating low pressure at the equator, along with rain-producing
cumulonimbus clouds. The rising air eventually cools and sinks back to the
surface at latitudes roughly 30° north and south of the equator.
Celestial
bodies, the sun, moon, planets, and stars have provided us a reference for
measuring the passage of time throughout our existence. Ancient
civilizations relied upon the apparent motion of these bodies through the
sky to determine seasons, months, and years.
Many people have heard a sonic boom, but few have seen one. When
an airplane travels at a speed faster than sound,
Anders
Celsius should be recognized as the first to perform and publish careful
experiments aiming at the definition of an international temperature scale
on scientific grounds. In his Swedish paper "Observations of two persistent
degrees on a thermometer" he reports on experiments to check that the
freezing point is independent of latitude (and also of atmospheric
pressure!). He determined the dependence of the boiling of water with
atmospheric pressure ..
Antonov An-225 "Mriya" is the
world's largest aircraft. When it was built, it surpassed any airliner built
before by 50%. It was designed for the transportation of the Russian Space
Shuttle "Buran" by the Antonov Design Bureau (HQ in Kiev, Ukraine), which
already had built good and large cargo aircraft such as the Antonov An-124 "Ruslan". ...
This
is the story of how materials are made up from atoms. There are only about
100 kinds of atoms in all the Universe, and whether these atoms form trees
or tires, ashes or animals, water or the air we breath, depends on how they
are put together. The same atoms are used again and again....
The
era of large-scale electric power distribution arguably began on
August 26, 1895, when water flowing over Niagara Falls was diverted
through a pair of high-speed turbines that were coupled to two
5,000-horsepower generators. The bulk of the electricity produced at
about 2200 volts and used locally for the manufacture of aluminum
and carborundum. But the following year a portion was raised to
11,000 volts and transmitted twenty miles by wire to the city of
Buffalo, where it was used for lighting and street cars.
.....continue
The
bat can sense in which direction the insect is moving based on the pitch of
the echo. If the insect is moving away from the bat, the returning echo will
have a lower pitch than the original sound, while the echo from an insect
moving toward the bat will have a higher pitch. This difference is due to
the Doppler effect
The
shortening of the fibers creates mechanical force, or muscle tension.
Whether the muscle itself changes length (same-force or isotonic
contraction) or not (same-length or isometric contraction) depends upon the
load attached to the muscle.
Einstein
was simply ahead of his time. More than half a century later, his dream
of a unified theory has become the Holy Grail of modern physics. And a
sizeable part of the physics and mathematics community is becoming
increasingly convinced that string theory may provide the answer.
Historical
standard platinum iridium meter bar.
The modern length standard has evolved over a period of 200 years which
has brought it to a point where it can be continually improved without the
necessity of changing its definition. We may suspect that the developers of
the first length standard were as unprepared to predict present day
developments as we are to predict the advances that will be made in the next
century.
For
centuries, the way in which the sun and stars produce their energy
remained a mystery. During the Twentieth Century, scientists discovered that
they produce their energy by the fusion process. Einstein's theory that mass
can be converted into energy provided the basis for understanding fusion.
...
One
of the most interesting things about a cell phone is that it is actually
a radio -- an extremely sophisticated radio, but a radio nonetheless.
......There's a lot of talk in the news these days about whether or not cell
phones emit enough radiation to cause adverse health effects. ....
Speed:
Formula None
Before
1820, the only magnetism known was that of iron magnets and of lodestones.
This was changed by a little-known professor of science at the University of
Copenhagen, Denmark, Hans Christian Oersted. 